#pragma GCC optimize(2)
#include <bits/stdc++.h>

using namespace std;
#define int long long
const int inf = 0x3f3f3f3f3f3f3f3f;

void solve()
{
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    vector<int> b;
    for (int i = 0; i < n - 1; i++) b.push_back(a[i] ^ a[i + 1]);
    int g = 0;
    for (int i = 0; i < b.size(); i++) g = gcd(g, b[i]);
    cout << g << endl;
}

signed main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int _ = 1;
    //cin >> _;
    while (_--)
    {
        solve();
    }
    return 0;
}